Ferrous base alloy



June 1964 A. T. CAPE ETAL FERROUS BASE ALLOY Filed Dec. 7, 1961 INVENTORS V. KOUGH ATTORNEYS United States Patent FERRGUS BASE ALLGY Arthur T. Cape, Monterey, Califi, Enrico M. Zampieri, laramus, N..T., and Harry V. Kough, Chester, Pa, assignors to Coast Metals, Inc., Little Ferry, N.J., a

corporation of Delaware Filed Dee. 7, 1961, Ser. No. 157,633 1 Qlairn. (Cl. 75--128) This invention relates, as indicated, to ferrous base alloys, but has reference more particularly to improvements in the alloy disclosed in US. Patent No. 2,337,083.

In US. Patent No. 2,337,083, there is described a ferrous alloy containing about .30 to about 1.50% carbon, chromium and nickel in amounts of from about 2% to about 7% of each, and from about to about molybdenum, the alloy being characterized by the fact that its hardness in the as-cast or deposited state decreases With increasing carbon content, the hardness varying substantially in direct proportion to the increase in carbon. This variation in hardness was stated to be due to the retention, in large quantities, of austenite, due to the increase in carbon.

This retention of large quantities of austenite made the alloy extremely difficult to machine, and therefore limited the usefulness or field of application of the alloy.

We have found that under certain conditions, an alloy of this character can be rendered machinable by increasing the hardness of the alloy with increase in carbon content, within a range of from about .25 to .70% carbon.

This is accomplished by using nickel, in a limited range of from 0.5 to 2.75 and using chromium in amounts up to 8% which are always in excess of the nickel, and which vary, as to the minimum range which is used, in the relationship shown in the accompanying drawing, which is a part of the application.

Referring to the drawing, it will be seen that in the range of from 0.5 to 1% nickel, the minimum of chromium which can be used is 2.5%, up to a maximum of 8%. In the range of from 1 to 1.5% nickel, the minimum amount of chromium which can be used varies in direct proportion to the nickel content, from 2.5 to 2.75 and up to a maximum of 8%. In the range of from 1.5% to 2% nickel, the minimum amount of chromium which can be used varies in direct proportion to the nickel content, from 2.75 to 3.5%, and up to a maximum of 8%. In the range of from 2% to 2.5% nickel, the minimum amount of chromium which can be used varies in direct proportion to the nickel content, from 3.5% to 4.25%, and up to a maximum of 8%. In the range of from 2.5% to 2.75% nickel, the minimum amount of chromium which can be used varies in direct proportion to the nickel content, from 4.25% to 5%, and up to a maximum of 8%.

3,136,630 Patented June 9, 1964 The claimed alloy range is thus depicted by the area within the graph, all of the alloys within this area having a ferritic base, which renders the alloys machinable.

The alloys also contain from 2 to 4% molybdenum, and may contain, optionally, boron in amounts up to about .5 and silicon, in amounts up to about 1.25%, the balance of the alloy being substantially all iron.

A preferred alloy, within the range claimed, is one consisting of about .35 carbon, about 1.7% nickel, about 6% chromium, about 3.5% molybdenum, about 001% boron, and about 1% silicon, the balance being substantially all iron.

The alloys may be used in the form of welding rods, for arc welding, oxyacetylene Welding, submerged arc welding, etc. For this purpose, they may be supplied in the form of Wire, in which the alloying ingredients, without the nickel, form the wire, and the nickel, in an amount sulficient to provide the correct composition of material in the weld is provided in the form of a coating for the wire.

Where the phrase the balance being substantially all iron is used in the claim, this is to be construed to permit the inclusion in the alloy, in trace or residual amounts, of one or more of the elements, manganese, sulphur and phosphorus.

Having thus described our invention, we claim:

A machinable iron-base alloy consisting of from .25 to .70% carbon, from 0.5 to 2.75% nickel, from 2.5 to 8% chromium, and from 2 to 4% molybdenum, the balance of the alloy being substantially all iron, the mini mum amount of chromium present being in accordance with the following table:

(a) When the nickel is from 0.5 to 1%, the minimum amount of chromium is 2.5%

(b) When the nickel is from 1 to 1.5%, the minimum amount of chromium varies in direct proportion to the nickel, from 2.5 to 2.75

(c) When the nickel is from 1.5 to 2%, the minimum amount of chromium varies in direct proportion to the nickel, from 2.75 to 3.5%

(d) When the nickel is from 2 to 2.5%, the minimum amount of chromium varies in direct proportion to the nickel, from 3.5 to 4.25%

(e) When the nickel is from 2.5 to 2.75 the minimum amount of chromium varies in direct proportion to the nickel, from 4.25 to 5%.

References Cited in the file of this patent UNITED STATES PATENTS 1,987,841 Rittershausen Jan. 15, 1935 2,327,490 Bagsar Aug. 24, 1943 2,337,083 Cape Dec. 21, 1943 2,624,687 McMullan Jan. 6, 1953 2,654,683 McMullan Oct. 6, 1953 

